Cooling arrangement for shaft furnaces

ABSTRACT

The cooling arrangement comprises spaced apart cooling tubes arranged in a frame and interconnected with metallic tie plates. For decreasing thermal stresses without loss of strength throughout the structure, each tie plate is tangentially welded with its edge portions to the adjacent cooling tubes on both the shell and the furnace sides thereof. Each tie plate may be tangentially welded to one adjacent cooling tube and to the other it may be welded on the portion of its surface defined by an arc between tangents to this arc from the location where the tie plate is tangentially welded. The cooling tubes and the tie plates may be provided with fins and, the tie plates and the fins and as well as the walls of the frame have expansion clearances or slots. The frame is filled with a refractory material serving to protect the whole cooling arrangement.

BACKGROUND OF THE INVENTION

The present invention relates to cooling arrangements for shaftfurnaces.

Known in the art is a cooling arrangement for blast furnaces (JapanesePatent Publication No. 45-14642, Nat. Cl. 10A521, published in 1970),comprising spaced apart metallic cooling tubes arranged so that with thecooling arrangement in position the tubes are adjacent to the furnaceshell, are substantially parallel to its longitudinal generating lineand are interconnected with metallic tie plates by welding, while thespace between the cooling tubes and the tie plates interconnecting thesame tubes is filled with a refractory material. In the prior artcooling arrangement, the cooling tubes extend along the height of thecooling zone of the furnace shaft and are interconnected by tie platesalong both the height and the perimeter of the furnace shaft to therebyprovide a rigid structure.

This structure is subjected to extreme thermal loads through the heightand the perimeter of the furnace shaft. Under these conditions a rigidstructure with the tubes interconnected as hereinabove describedexperiences considerable thermal stresses leading to break-away of thetie plates from the cooling tubes and, consequently, to gas leakagethrough the cooling arrangement followed by overheating of the furnaceshell resulting its warping and wreckage.

Moreover, due to the structural features the prior art coolingarrangement poses problems in its construction since a stringentobservance of its design characteristics is required. Construction ofthe cooling arrangement is further complicated by the fact that this canbe carried out in the furnace only during major repairs or inconstructing the furnace to thereby extend the repair (construction)period and to make use of a special-purpose equipment at theconstruction site. Furthermore, it is to be appreciated that the coolingarrangement is assembled in a restricted space.

It is also to be kept in mind that making such long welds produces morestresses throughout the structure.

During a furnace run, the refractory material disintegrates and fallsdown to uncover the cooling tubes and therefore to increase heat losses,which result in an excessive consumption of fuel.

The uncovered tubes are exposed to an abrasive action of the dusty gasesand the charge materials.

SUMMARY OF THE INVENTION

The invention is directed to the provision of a cooling arrangement forshaft furnaces, which is more adapted to construction and whoseresistance to mechanical and thermal loads is increased by changing theinterconnection between the cooling tubes to thereby offer a reliableprotection for the furnace shell from the action of the furnaceatmosphere.

The invention provides a cooling arrangement for shaft furnaces,comprising at least two spaced apart metallic cooling tubes arranged sothat with the cooling arrangement in position they are adjacent to thefurnace shell, are substantially parallel to its longitudinal generatingline, and are interconnected with metallic tie plates by welding, whilethe space between the cooling tubes and the tie plates interconnectingthe same tubes is filled with a refractory material. Further, each tieplate is tangentially welded to an adjacent tube of at least two coolingtubes with at least one edge portion along the generatrix of the tubesurface on the shell side and between adjacent tie plates along theheight of the cooling arrangement there is a spacing extending along thelength of the tie plate laterally of the cooling arrangement, the latterbeing embraced along the perimeter thereof by a metallic frame havingwalls extending along the cooling tubes and slotted their entire widthto compensate for heat expansion.

Such arrangement provides a more reliable protection for the furnaceshell since this arrangement has an increased resistance to mechanicaland thermal loads due to a novel interconnection between the coolingtubes which lies in the fact that each tie plate is tangentially weldedto the tubes with at least one edge portion thereof and along thegeneratrix of the tube surface, while there is a spacing between the tieplates as well as spacings or slots in the frame walls. By virtue ofthese features the cooling arrangement has become less rigid, but itsstrength has increased because thermal stresses are compensated and thewelding stresses heretofore developed in manufacture are nonexistent.

Such arrangement is also more adapted to construction inasmuch as thetie plates can be readily set out tangentially to the cooling tubes tobe connected instead of setting them out in a diametric plane and thespacings between the tie plates naturally interrupt or discontinue theweld, which makes it easier to assemble the cooling arrangement even inthe furnace.

It is to be noted that the cooling arrangement of the invention can bemanufactured outside the furnace and then put up in position. This hasbecome possible because the cooling tubes are embraced by a frame toprovide a self-contained cooling element. It will be readily understoodby those skilled in the art that such cooling elements may be of anydimensions depending on the application.

Various modifications may be made in the invention without departingfrom the spirit and scope thereof.

Thus, the second edge portion of each tie plate may be tangentiallywelded to an adjacent cooling tube on the shell side or the furnace sidethereof as well as in the region defined by tangents to thecircumference bounding the tube on its outer surface with the tangentsoriginating frpom the location where at least one edge portion of eachtie plate is welded.

Also, the tie plates may be provided with fins extending from thefurnace side thereof to the interior of the furnace. The fins may beflat or bent toward a descending charge material.

It is suitable to provide fins extending laterally from the tubes andencompassing more than half their circumference from the furnace sidethereof. Such fins may be horizontal, at an angle to the cooling tubestoward a descending charge material, and they may be bent toward adescending charge material. Such arrangement improves cooling of therefractory material and holding the lining slag with the remainingfragments of the refractory material after its possible disintegration,which reduces heat losses and, accordingly, saves fuel.

It is a good practice to space the fins apart from each other both onthe cooling tubes and on the tie plates in order to compensate forthermal stresses.

According to a further aspect of the invention the cooling tubes may beprovided with fins welded thereto along the generatrix in a spaced edgeto edge relationship to compensate for heat expansion.

In this case the refractory material is cooled better.

The fins welded along the tube generatrix are preferably T-shaped likein cross-section. Such fins reduce destructible action of the chargematerials on the refractory material and the cooling tubes as well ashave a contributing effect on the wear resistance of the coolingarrangement as a whole.

The above features of the invention make possible the provisions of pinson the furnace side of the tie plates and of the fins, the latter mayhave the pins on both the furnace and the shell sides. The pins on thetie plates and on the fins provide for enhancing the cooling rate and,consequently, the durability of the cooling arrangement. Moreover, thepins are at least partially helpful in retaining of the refractorymaterial that may disintegrate.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a front elevational view of the cooling arrangement withoutthe refractory material.

FIG. 2 is a sectional view taken along the line II--II in FIG. 1.

FIG. 3 is a sectional view taken along the line III--III in FIG. 1.

FIG. 4 is a sectional view illustrating an alternative embodiment of thecooling arrangement shown in FIG. 3.

FIG. 5 is a sectional view illustrating a further version of thearrangement of the fins on the vertical wall as shown in FIG. 2.

FIG. 6 is a sectional view illustrating another embodiment of the finarrangement shown in FIGS. 2 and 5.

FIG. 7 is a sectional view illustrating another version of the finarrangement as shown in FIGS. 2, 5 and 6.

FIG. 8 is a sectional view showing another embodiment of the inventionas shown in FIG. 2.

FIG. 9 is a cross-sectional view of another embodiment of the coolingarrangement as shown in FIGS. 3 and 4.

FIG. 10 is another version of the cooling arrangement as shown in FIG.9.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates a cooling arrangement for cooling the shell of shaftfurnaces, preferably blast furnaces. The front elevation shown herein isa cooling arrangement seen from the interior of the furnace orrepresenting its furnace side and comprising steel cooling tubes 1connected via the pipes 2 to a coolant source (not shown).

While FIG. 1 illustrates the cooling arrangement as having four coolingtubes 1, it may have two cooling tubes each of an L-shape configurationand including sections 1a and 1b, section 1a usually running verticallyand section 1b horizontally. At least two such tubes forming anessentially closed rectangle provide for an effective protection of thefurnace shell in the zone of the location of such cooling arrangement.

Also, the cooling tubes 1 as well as other metallic components may notnecessarily be made of steel, as other metals or alloys suitable forspecific thermal or chemical conditions of a specific furnace can beused.

The cooling tubes 1 are interconnected with steel tie plates 3. Each tieplate 3 has a first edge portion 4, which in this case is the edge ofthe tie plate, and a second edge portion 5, which is also the edge ofthe same tie plate but an opposite end. As cn be seen in FIG. 3 the edgeportion 4 and the edge portion 5 of each tie plate 3 are tangentiallywelded to a corresponding adjacent cooling tube 1 along the generatingline on the side facing the furnace shell 6 or the shell side of thetubes. The tie plates 3 are arranged so that there is a spacing 7between adjacent tie plates along the height of the cooling arrangement,each spacing extending along the length of each tie plate laterally ofthe cooling arrangement. The cooling tubes 1 and the tie plates 3assembled as herein described are embraced by a metallic frame 8 of agenerally rectangular form and having horizontal 9 and vertical 10walls. The walls 9 and 10 of the frame 8 are arranged with respect tothe tubes 1 so that each wall extends along the respective tube 1 or thesection thereof. In this exemplary cooling arrangement the verticalwalls 9 extend along the sections 1b. The walls 9 are slotted as at 11through their whole width.

In the exemplary structure embodying the invention shown in FIGS. 1through 3, the wall of the tube sections 1a and the vertical walls 10are spaced apart and this space is bridged by the tie plates 3. Theslots 11 as are provided between the spacings 7 but they may alsocoincide with the spacings 7, though this arrangement makes thestructure less rigid. The cooling tubes 1, the tie plates 3, and theframe 8 form a receptacle to be filled with a refractory material suchas refractory concrete. The cooling arrangement, assembled and filledwith a refractory material, is a self-contained cooling element whichcan be built to desired dimensions and used as a part of a largercooling system. The cooling arrangement may be assembled from suchcooling elements, which were built outside the furnace, to therebyconsiderably facilitate both the manufacture of each individual elementand the assembly of the whole cooling system. The space between thefurnace shell 6 and the shell side of the cooling arrangement is filledby conventional methods.

According to an alternative embodiment shown in FIG. 4 the second edgeportion 5 of each tie plate 3 is tangentially welded to a correspondingadjacent cooling tube 1 on the furnace side thereof. In this case thewall 10 may be welded to an adjacent cooling tube 1, namely the section1a as can be seen in FIG. 4.

From the above description it follows that the second edge portion 5 maybe welded to an adjacent cooling tube in the region defined by tangentsto the circumference bounding the adjacent cooling tube on its outersurface, the tangents originating from the location where the first edgepontion 4 is welded to a corresponding tube 1, i.e., between the weldlocation on the shell side of the tube 1 (see FIG. 3) and the weldlocation on the furnace side of the tube 1 (see FIG. 4). If the firstedge portion 4 is welded at the point of tangency then assembly of sucha cooling arrangement will not be complicated.

According to another embodiment of the invention the tie plates 3 areprovided with fins 12 on the furnace side thereof as illustrated inFIGS. 1-4. The fins 12 may also be provided on the cooling tubes 1 as isspecifically shown in FIG. 1 or on the tie plates and the adjacent tubesas can be seen in FIG. 4.

Referring to FIG. 3, the fins 12 are arranged laterally from the coolingtubes 1 and encompass more than half their circumference. The fins 12are preferably arranged alternately in the vertical plane (FIG. 1),which arrangement provides for a more effective cooling of therefractory material while the cooling arrangement has a relatively lowmetal content. The fins 12 may be flat sheets horizontally extendinginto the interior of the furnace but within the thickness of the coolingarrangement (FIGS. 1 to 3). These fins may also be arranged at an angleto the cooling tubes 1 and directed toward the descending chargematerials (FIG. 5) or they may form a combination of the above forms(FIG. 6).

A different form of the fins 12 is shown in FIG. 7 where the fins arebent toward the descending charge material.

FIG. 8 illustrates an alternative embodiment of the invention whereinthe cooling tubes 1 or their vertical portions 1a are provided withlongitudinal fins 13 extending along the generatrix of the portions 1aand to the furnace interior. Each cooling tube 1 preferably has severalfins 13 arranged so that there are spacings 14 between them tosompensate for thermal stresses or there may be on fin per tube which isslotted laterally of the tube at specific locations.

As an alternative, the fins 13 are T-shaped in cross-section which isbest seen in FIG. 9. In other words a flange 15 is welded to the fins orfin 13 and the flange may be slotted laterally or may be composed ofseveral similar flanges arranged so that there is a spacing 16 betweenthem (FIG. 8). The slots or spacings 16 may coincide with the spacings14, or may not as in FIG. 8.

Referring to FIG. 9 where a fragment of a cooling arrangement of theinvention is shown in cross-section, the cooling tubes 1 are connectedby the tie plates 3 tangentially welded to the tubes 1 on the shell sidethereof and the space between the tubes 1 is filled with a refractorymaterial 17. Each cooling tube 1 has one fin 13 (or several such finsarranged in a spaced edge to edge relationship along the generatrix ofthe tube surface). The fins 13 are provided with flanges 15 having pins18 extending from the shell side of the flanges. Also, similar pins maybe provided on the furnace side of the tie plates 3 as is best seen inFIG. 9. Each tube 1 may also have several radially extending T-shapedfins or radial fins 13 with flanges 15.

In operation, the coolant flows through the inlet pipes 2 shown at thelower portion of the cooling arrangement (FIGS. 1 and 2) and into thecooling tubes 1 to take the heat from the refractory material 17 heatedby the charge materials and the furnace gases. The heated coolant flowsout of the cooling arrangement through the outlet pipes 2 shown at theupper portion of the cooling arrangement (FIGS. 1 and 2). The coolingtubes 1 are heated and therefore expand, but stresses do not develop inthem due to the slots or spacings 7 between the tie plates 3 and due tothe slots 11 in the walls of the frame 8. The fins 12 are, on the onehand, acting as reinforcing members for the refractory material, and onthe other hand the fins 12 serve as a cooling means lowering thetemperature of the refractory material and increasing its thermalstability (operative capacity).

The T-shaped fins 13 afford improved protection for the refractorymaterial 17 from abrasion and diminish the area of contact of therefractory material with the charge and the furnace gases.

The fins 12 bent toward the descending charge material or arranged at anangle to the cooling pipes 1 provide for an improved holding of thelining slag and if the lining slag is not present they provide animproved holding of the components of the refractory material, whichgenerally decreases abrasion of the cooling tubes 1 and improvesoperating capacity of the cooling arrangement. The pins 18 also serve asa reinforcing means for the refractory material and improve heattransfer from the same material.

INDUSTRIAL APPLICABILITY

The invention is useful is shaft furnaces, preferably blast furnaces.

We claim:
 1. A cooling arrangement for shaft furnaces comprising:(a) atleast two spaced apart metallic cooling tubes arranged in the coolingarrangment in a position adjacent to a shell side of the shaft furnace,said cooling tubes substantially parallel to a longitudinal generatingline of said shell side; (b) at least two tie plates interconnectingsaid cooling tubes, each of said tie plates is tangentially welded to anadjacent tube of said cooling tubes with one edge portion of said tieplate along a generatrix of one surface of said adjacent tube of saidcooling tubes on said shell side and said tie plates are adjacentlyarranged and separated by a spacing along a height of said coolingarrangement which extends laterally along a length of said tie plate;(c) a refractory material filling a space between said cooling tubes andsaid tie plates; and (d) a metallic frame embracing a perimeter of saidcooling arrangement having a vertical wall extending along said coolingtubes, said wall being slotted along an entire width to compensate forheat expansion.
 2. A cooling arrangement according to claim 1, whereineach of said tie plates is comprised of a second edge portiontangentially welded to said adjacent cooling tube of said cooling tubeson said shell side.
 3. A cooling arrangement according to claim 2,wherein said tie plates further comprise pins facing a furnace side ofsaid shaft furnace.
 4. A cooling arrangement according to claim 1,wherein said second portion of said tie plate is tangentially welded toa furnace side of said adjacent cooling tube of said cooling tubes.
 5. Acooling arrangement according to claim 1, wherein said second edgeportion of said tie plate is welded to said adjacent cooling tube in aregion defined by a tangent to a circumference bounding said coolingtube on an outer surface, said tangent originating from a location whereat least one of said first edge portion and said second edge portion ofsaid tie plate is welded.
 6. A cooling arrangement according to claim 4or 5, wherein said tie plates have fins on a surface side.
 7. A coolingarrangement according to claim 6, wherein said fins are bent toward adescending charge material.
 8. A cooling arrangement according to claim1, wherein said cooling tubes have fins extending laterally from saidtubes, said fins encompassing more than half a circumference of saidfins from said furnace side of said shaft furnace.
 9. A coolingarrangement according to claim 8, wherein said fins extend horizontallyfrom said cooling tubes.
 10. A cooling arrangement according to claim 8,wherein said fins extend at an angle to said cooling tubes in adirection toward said descending charge material.
 11. A coolingarrangement according to claim 8, wherein said fins are bent toward saiddescending charge material.
 12. A cooling arrangement according to claim1, wherein said fins of said cooling tubes are welded together alongsaid generatrix of said surface of said adjacent tube of the coolingtubes in a spaced edge-to-edge relationship to compensate for heatexpansion.
 13. A cooling arrangement according to claim 12, wherein saidfins of said cooling tubes appear T-shaped in cross-section.
 14. Acooling arrangement according to claim 12, or 13, wherein said fins areprovided with pins.